PTL 1 discloses an expansion valve having a power element on which two diaphragms are stacked and peripheral edges thereof are joined to each other over the entire circumference. A fluid enclosing space having an enclosed fluid is sealed between the two diaphragms in the power element disclosed in PTL 1. If a temperature of the enclosed fluid rises, the two diaphragms are deformed so as to respectively expand, and a flow rate of a fluid to be decompressed by the expansion valve is controlled according to a deformation amount thereof.
The expansion valve disclosed in PTL 1 includes the two diaphragms. Accordingly, compared to an expansion valve including one diaphragm, it is possible to decrease the deformation amount per one diaphragm in order to obtain a predetermined deformation amount of the power element which corresponds to a temperature change in the enclosed fluid.
PTL 2 discloses an expansion valve including a first channel which has a decompressing channel for decompressing a flowing fluid and in which the flowing fluid flows, an expansion unit which has an enclosed fluid and which expands in a uniaxial center direction as the temperature of the enclosed fluid rises, and a flow rate control unit which controls a flow rate of the flowing fluid in the first channel in accordance with an expansion amount of the expansion unit. In addition to the above-described first channel, the expansion valve disclosed in PTL 2 includes a low pressure channel serving as a second channel in which the flowing fluid flows after being decompressed in the first channel. A power element which is the expansion unit is disposed so as to sense a temperature and a pressure of the flowing fluid which flows in the low pressure channel. A fluid having multiple refrigerants mixed therewith is enclosed as the enclosed fluid in the power element.